Drug interactions
Atenolol-chlorthalidone + Sulfamethoxazole
Severity: Moderate
Atenolol-chlorthalidone and Sulfamethoxazole: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Sulfamethoxazole is usually given with trimethoprim, which can cause hyponatremia and hyperkalemia. Chlorthalidone also promotes sodium loss, so the combination may increase the risk of low sodium, particularly in older adults. Beta-blockers may add to hyperkalemia risk.
What this interaction means in plain words
Atenolol-chlorthalidone and Sulfamethoxazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Additive sodium loss from thiazide-like diuresis and trimethoprim's ENaC-blocking effect in the distal nephron.
What to do
Monitor serum sodium and potassium within the first week of co-trimoxazole therapy, especially in the elderly. Stop or change therapy if significant hyponatremia develops.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Atenolol-chlorthalidone
Frequently asked questions
Can I take Atenolol-chlorthalidone with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Atenolol-chlorthalidone and Sulfamethoxazole can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Sulfamethoxazole is usually given with trimethoprim, which can cause hyponatremia and hyperkalemia. Chlorthalidone also promotes sodium loss, so the combination may increase the risk of low sodium, particularly in older adults. Beta-blockers may add to hyperkalemia risk.
How serious is the interaction between Atenolol-chlorthalidone and Sulfamethoxazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor serum sodium and potassium within the first week of co-trimoxazole therapy, especially in the elderly. Stop or change therapy if significant hyponatremia develops.
What other medicines interact with Atenolol-chlorthalidone?
MediHelp also lists interactions of Atenolol-chlorthalidone with, for example, Acebutolol, Aldesleukin, Amiodarone. The full list is on the Atenolol-chlorthalidone page.
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